Rotary hammer for feed mills



July s, 1 952 BALL 2,602,597

ROTARY HAMMER FOR FEED MILLS Filed June 6, 1951 7 J41 4 a A 28 g A 36- l 2 .f 1 36 Z/ 33 26a v //W/vr0R //3 Y 656410 L. BALL HTTURNEZ Patented July 8, 1952 UNITED STATES PATENT OFFICE ROTARY HAMMER FOB, FEED MILLS Gerald L. Ball, Council Bluffs, Iowa Application June 6, 1951, Serial No. 230,198

2 Claims. 1

This invention relates generally to rotary hammer assemblies for feed grinding mills and in particular to a rotary hammer for such a hammer assembly.

Hammermills generally employ hammer assemblies comprised of a series of hammers pivotally hung for swinging movement on a rotatable shaft-supported disk. These hammers are rotated in succession over a concave screen through which passes the grain or other material which "is ground by the hammers. Initially the hammers are formed with sharp cutting corners for cutting and breaking the grain against the screen or concave. When these corners are worn round the efliciency of the hammers is reduced, and the hammers are then turned side for side to present a new corner to the grain. Due to the hard wearing action of the grain on the hammers, hammer replacements must be frequently made.

It is an object of this invention, therefore, to provide an improved rotary hammer.

A further object of this invention is to provide a rotary hammer which is of an economical manufacture, of a compact and simple design, and capable of efiiciently grinding grain over an extended period of use.

A feature of this invention is found in the provision of a rotary hammer which is formed from a flat body member having a head member of a loop shape at one end thereof, the side sections of which 100p are arranged in planes spaced apart laterally of the body member and brought together at their inner ends to close the loop. By virtue of this spaced relation of the side sections the head member is provided with a plurality of cutting edges and can be completely case hardened to effectively increase the wearing life of the cutting edges.

Further objects, features and advantages of this invention will become apparent from the following description when taken in connection with the accompanying drawing in which:

Fig. 1 is a fragmentary sectional view of a hammer mill showing a rotary hammer assembly, embodying the hammer of this invention, in assembly relation with a concave;

Fig. 2 is a perspective view of a hammer of this invention;

Fig. 3 is a longitudinal sectional view taken along the line 33 in Fig. 2;

Fig. 4 is a developed side elevational view of the hammer of this invention; and

Fig. 5 is a fragmentary perspective view of the head of the hammer after the hammer has been in use.

With reference to the drawings there is illustrated in Fig. 1 a rotary hammer assembly Ill including a hammer ll of this invention, four of which are shown. Each hammer II has a head member l2 at one end and is pivoted at its other end l3 on a rotatable disk or plate M, for swinging movement in the plane of the disk which is mounted on a shaft [6. The assembly I0 is arranged, in a well known manner, relative to a screen or concave ll of a hammer mill, such that the grain being ground is out against the concave I1, and with the ground grain passing through the perforations l8 in the concave out of the cutting zone of the hammers H.

A hammer H (Figs. 2 and 3) is formed from a single flat bar member so as to have a flat body member I9 with a loop shaped head member I2 at one end thereof. A hole 21 in the body member end l3 receives a pivot pin 22 for pivotally securing the hammer to the disk [4.

The side sections 23 and 23a of the loop shaped head member l2 extend longitudinally of the body member I9 and are arranged in a spaced relation laterally offset from the plane of the body member 19 to provide an opening or passage 24 of an elongated oval shape extended.

transversely of the body member. This spaced relation of the side sections 23 and 23a is accomplished by providing at the inner ends of these sections laterally offset shoulders or stop portions 26 and 26a, respectively, which extend toward each other, in directions laterally of the body member 19, into abutting engagement so as to close the inner end 21 of the head member loop. The shoulder 26 terminates in a straight portion 28 which is positioned flat against the side 29 of the body member I9. A rivet 3| extended through the portion 28 and the body member l9 positively holds the shoulders 26 and 26a against each other and the loop against coming open, namely, prevents any movement of the side section 23 away from the side section 223m at the shoulders 26 and 26a.

By virtue of this construction it is seen that the side sections 23 and 23a of the head member loop are arranged in planes, parallel with the plane of the body member l9, but arranged to opposite sides of the plane of the body member I9. The head member I2 is thus formed at each side of the hammer I I with a plurality of cutting edges 32. As a result of the passage 24, which as best appears from Fig. 3 is of a Width substantially equal to the thickness of the body member I9, the side sections 23 and 23a can be efiectively case hardened so as to increase the wearing life of the cutting edges 32. Also the side section 23 gives added weight to the hammer head [2 whereby to facilitate the grinding action of the cutting edges 32, since this added weight of the section 23 tends to keep the hammers radially extended from the disk l4, as the hammer sweeps over the concave [1.

By virtue of the case hardening of the opposite side surfaces 35 of a side section 23 and 23a, the cutting edges 32 are retained efiective after the head I2 has become worn by use, as shown in Fig. 5. Thus as the junction 38 of the side sections 23 and 23a becomes worn the sections 23 and 23a become rounded, as indicated at 31; at the free end of the head member 12. However, since the surfaces 35 are case hardened they are worn to a lesser degree than thematerial-therebetween, so that the edges of the side sections 23 and 23a, over their rounded portions 31, are

of a concave contour. The cutting edges 32 are thus more pronounced and their efliciency for grinding improved, after the hammer has been in use.

In the manufacture'of a hammer II the bar member from which the hammer-is formed, and indicated at 33 in Fig. 4, is formed in a pressing operation with a laterally depressed longitudinally extended section 34 the ends-of which are defined by the shoulders 26 and 26a, and with the shoulder 26 terminating inthe flat portion 28 which is located in the plane of the bar member 33. The depressed section 34 is then bent or doubled upon itself, in the direction indicated by the arrow 36, to locate the shoulder 26 opposite from, and in engagement with the shoulder 2611. It is seen, therefore, that the manufacture of the hammer H is economical and with the spaced relation between the side sections 23 and 23a being positively determined and maintained by the abutting engagement of the shoulders 26 and 26a and the securing of such shoulders against each other by the rivet 3 I.

Although the invention has been described with respect to apreferred embodiment thereof it is to be understood that it is not to be so limited .since changes can be made therein which are within the full intended scope of this invention as defined by the appended claims.

I claim:

l. A rotary pivoted hammer comprised of a flat bar member having a lateral fastening hole at one end thereof, said rotary hammer being adapted to rotate about said fastening hole, said member having an elongated head member of a loop shape formed at the opposite end thereof, said head member having flat side sections which are case hardened and separated apart in planes to opposite sides of, and in a parallel relation with, the plane of said bar member, co-acting stop portions on said bar member and head member arranged for abutting engagement to close the inner end of said head member, and means for holding said stop portions together against separation, said stop portions being of a length laterally of said bar member to provide for the .ateral dimension of said head member being equal to substantially three times the thickness of said bar member, said hammer being thus adapted to present during its rotary action the four case hardened radial edges of said side sections of the head member to the material to be acted upon by said hammer.

2. A rotary, radially elongated hammer comprised of a flat elongated bar member, a head member of an elongated closed loop shape formed at one end of said bar member, the two elongated sides of said loop being case hardened and of substantially the same thickness and width as said bar member and positioned parallel thereto, means for holding said two elongated sides in a predetermined spaced relation, said bar member having a lateral fastening hole at the opposite end thereof whereby said hammer is adapted to be rotated in the plane of said bar member so that the case hardened radial edges of said head member are presented to the material being acted upon.

GERALD L. BALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 14,886 Campbell June 22, 1920 1,871,489 Ammon Aug. 16, 1932 2,208,892 Bukacek July 23, 1940 2,237,510 Tankersley Apr. 8, 1941 2,319,629 Poese May 18, 1943 FOREIGN PATENTS Number Country Date 356,276 Italy Jan. 27, 1938 

